Base plate in compression
The resistance of concrete in compression is defined according to EN 1993-1-1 by the following formula
Base dimensions
Where is: | βj |
|
fcd |
| |
kj |
|
The factor kj is calculated using expression
Where is: | a, b |
|
a1, b1 |
| |
h |
|
The values a1 and b1 are calculated using following expressions
The assumption is, that the stress is distributed uniformly under the active area. This area consists of the column cross-section and surrounding are with maximum distance c from the edge of the cross-section. The thickness c is given by formula
Where is: | t |
|
fy |
| |
fj |
| |
γM0 |
|
The active areas for column web and flange
The active area under the base plate
Stiffness
The deformation between base plate and concrete surface for force F is calculated using expression
where the shape factor α depends on material characteristics. Following formula is used for concrete foundation and steel base plate according to (Wald, Sokol; 1996)
Where is: | δr |
|
α |
| |
Ec |
| |
L |
| |
ar |
|
The stiffness is calculated in accordance with EN 1993-1-8 using formula
The effective width of T-stub ar can be replaced for elastic deformations by the following width (ed.Weynand; 1999):
Where is: | tw |
|
t |
|
References
Wald F., Sokol Z.: Proposal of the Stiffness Design Model of the Column Bases, Connection v Steel Structures II, Behaviour, Strength, and Design, ed. Bjorhovde, Colson, Zandonini, Pergamon Press, London 1996, p. 237 - 249, ISBN 0-08-042821-5.
COST C1: Column Bases in Steel Building Frames, ed. K. Weynand, EC, Brussels 1999.